Printing mechanism for a calculating machine



H. J. CHALL 2,779,267

PRINTING MECHANISM FOR A CALCULATING MACHINE Jan. 29, 1957 9 ShetsSheet 1 Original Filed Jan. 29, 1954 m I. Do mm mm m mm m R m a M T s M m TV. T

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PRINTING MECHANISM FOR A CALCULATING MACHINE H. J. CHALL 9 Sheets-Sheet 2 Original Filed Jan. 29, 1954 Jan. 29, 1957 H. J. CHALL 2,779,257

PRINTING MECHANISM FOR A CALCULATING MACHINE Original Filed Jan. 29, 1954 9 Sheets-Sheet 3 (LA/1 Ill/I III I 1 I 111 v IIIII 1 1/ [III 1/ 11/1115 I73 5% a @3 I75 EIE- 5 H. J. CHALL Jan. 29, 1957 PRINTING MECHANISM FOR A CALCULATING MACHINE 9 Sheets-Sheet 4- Original Filed Jan. 29, 1954 BIT Jan. 29, 1957 H. J. CHALL 9 SheeIs-Sheet 5 PRINTING MECHANISM FOR A CALCULATING MACHINE Original Filed Jan. 29, 1954 Jan. 29, 1957 H. J. CHALL 2,779,267

PRINTING MECHANISM FOR A CALCULATING MACHINE Original Filed Jan. 29, 1954 9 Sheets-Sheet 6 Jan. 29, 1957 H. J. CHALL 2,779,267

PRINTING MECHANISM FOR A CALCULATING MACHINE] Original Filed Jan. 29, 1954 9 Sheets-Sheet '7 Jan. 29, 19 57 H. J. CHALL 2,779,267

PRINTING MECHANISM FOR A CALCULATING MACHINE Original Filed Jan. 29, 1954 9 Sheets-Sheet 8 H. J. CHALL Jan. 29, 1957 PRINTING MECHANISM FOR A CALCULATING MACHINE 9 Sheets-Sheet 9 Original Filed Jan. 29, 1954 PRINTING MECHANISM FOR A CALCULATING MACHINE Harold J. Chall, San Leandro, Calif., assignor to Friden Calculating Machine (30., Inc., a corporation of California Original application January 29, 1954, Serial No. 407,016. Divided and this application March 15, 1954, Serial No 416,123

Claims. (Cl. Mil-96) This invention relates to calculating machines and more particularly to printing mechanism for a calculating machine, such as an automatic adding machine, and constitutes a division of my application S. N. 407,016, filed January 29, 1954, for Calculating Machine.

It is among the objects of the invention to provide in a calculating machine, such as an automatic adding machine, an improved printing mechanism which is automatically actuated to print entry values, and total and subtotal values during corresponding operating cycles of the associated calculating machine; which performs its printing operation during a short interval of time inter mediate the length of the corresponding machine operating cycle; Which includes a plurality of ordinally arranged print wheels rotatable about a common axis, a platen of cylindrical shape opposed to the print wheels, and print wheel carriers providing for movement of the print Wheels individually toward and away from the platen; which has printing bosses spaced apart around the print wheels and provided with concave surfaces fitting the adjacent surface of the platen; which is arranged to print the two right-hand numerals at each printing operation and to block the printing operation of the left hand print wheels to the left of the leftmost significant numeral in a printed number; which maintains a constant angular relationship between the print wheels and the corresponding actuator sectors of the adding machine; which includes means for shifting a bicolored ink carry ing ribbon to print positive or additive values in one color and negative or subtractive values in a diiferent color; which has a tape feeding mechanism including a spacing control shiftable by entry and total printing mechanism of the machine to vary the spacing when a total or subtotal value is printed so that such total and subtotal values will be clearly distinguished from the entry values; which can print a number, such as a code or identifying number without entry of such number into the totalizing accumulator of the machine; and which is automatically returned to its retracted or full-cycle condition and zero setting after each printing operation and provides a clear view of the last printed value as soon as the printing mechanism is restored to full-cycle condition.

Other objects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawings wherein:

Fig. l is a diagrammatic illustration of the adding machine; 7

Fig. 2 is a view of the speed reducing gear train of the machine from the motor shaft to the cam shaft clutch, such speed reducing gear train being locaed at the right-hand side of the machine;

Pig. 3 is a front elevational view showing the machine cam shaft, the cams carried by the cam shaft, the location of the various cams along the cam shaft, and the ;.fnited States Patent C "2,779,267 Patented Jan. 29, 1957 form in plan view of the various cams, the view being taken from line 3-3 of Fig. 2;

Fig. 4 is a view showing a portion of the printing mechanism and particularly the print wheels, the print Wheel drive and the operating mechanism for the print wheels;

Fig. 5 is an elevational view of the actuator sector trail and lead earns, a print controlling cam and tenscarrying accumulator operating cam, and the mechanisms operated by these several cams from line 55 of Pig. 9;

Fig. 6 isa left side elevational view of the zero foil releasing cam for the printing mechanism and the mechanisms operated by this cam;

Fig. 7 is a general illustration of the ribbon shifting and tape feeding mechanism of the machine;

Fig. 8 is an elevational view from the left-hand side of the machine showing the crank for operating the return mechanism of the shiftable selector unit, the positive and negative transmission gear locking cam, the crank pin for releasing the control keys at the left-hand side of the keyboard and the print controlling cam together with the mechanisms operated by the several cams; and

Fig. 9 is a fragmentary top plan view showing the left-hand portion of the ribbon winding mechanism of the machine taken from the line 99 of Fig. 5.

Reference planes one parallel to the machine keyboard and another perpendicular to the one are indicated by lines A-A and B-B in Figs. 2, 4, 5 and 6.

With continued reference to the drawings and particularly to Fig. l, the adding machine of the present invention comprises, in addition to a suitable base, a suitable mechanism supporting framework and a mechanism cover, digitation mechanism A including a ten-key keyboard and a selection device having selector racks which are sequentially set to selected values from a higher to the lower order corresponding to values entered therein by manual depression of selected keys of the keyboard. It also comprises a printing mechanism D, and accumulator F, a power driven actuator C controlled by the selection device, power cycling mechanism B, a positive transmission E which drivingly connects the actuator with the printing mechanism at all times and alternatively connects the actuator with the selector mechanism orthe accumulator, a negative transmission G which at times connects the actuator to the accumulator, and a set of control keys I including an addition key, a subtraction key, a subtotal key, a total key, a print only key, a keyboard clearing key and a repeat addition key, all as diagrammatically indicated in Fig. l.

The power cycling device includes a motor driven cam shaft carrying a plurality of mechanism actuating cams and transmission means between the motor and the cam shaft eifective to turn the cam shaft through one complete rotation and bring it to a stop each time a control key of the machine is operated.

The positive and negative transmissions each have a neutral position and one transmission always occupies its neutral position while the other is in its operative position and both are bidirectionally operative to either transmit values from the selector mechanism to the accumulator or to transmit values from the accumulator to the printing mechanism.

The selector includes a unit laterally shiftable relative to the actuator and accumulator under control of an escapement mechanism as values are entered therein sothat the digits of a value of any number of digits within the capacity of the selector are simultaneously transmitted through the actuator to the printing mechanism and Q the accumulator upon the operation of any one of the addition, repeat addition or subtraction control keys.

Before operation of a value transmitting control key, a value can be cleared from the selector by operation of the keyboard clearing key without printing and without changing the total in the accumulator or feeding the printing tape.

The printing mechanism includes a paper tape on which the values are printed and an ink carrying ribbon which is preferably divided longitudinally into two portions of different colors. There is a tape feeding mechanism provided with a spacing adjustment which is effective to feed the tape in single space steps while entry values are being entered into the machine and printed and when a value is printed without entry into the machine accumulator, to double space the tape feed whenever a total or subtotal value is printed to thereby clearly offset the total and subtotal figures from the following column of entry value figures on the tape, and to interrupt tape feeding when the keyboard clearing key is depressed. There is also a ribbon shift means which is effective to position the ribbon in one color position when a positive or additive quantity is printed and in a different color position when a negative or subtractive quantity is printed and means are provided for winding the ribbon back and forth between spaced-apart ribbon spools.

The actuator includes a plurality of sectors which are power oscillated to accomplish an advance stroke and a return stroke each time a control key is operated. On

the advance stroke the actuators are moved to an extent determined by the positioning of the associated selector elements by the keyboard keys and, on the return stroke, are moved to their home or full-cycle position. On their advance stroke the actuator segments transmit the selector values through the positive transmission to the printing mechanism, the printing ribbon being shifted in accordance with Whether the addition or subtraction control key is operated, and on their return stroke transmit the value through either the positive or negative transmission to the accumulator in accordance with the operation of the addition or subtraction control key. The accumulator is operated. in one direction by the positive transmission and in the opposite direction bythe negative transmission and includes tens-transfer mechanism effective to transfer tens from any order to the next higher. order in either direction of operation. The accumulator will thus accumulate both'positive and negative values to a positive or negative total, as the case may be.

Because of mechanical requirements the positive zero setting of the accumulator is spaced one unit space from the negative zero setting with the consequence that when the positive zero setting is a series of zeros, the simultaneous negative setting is a series of nines and, conversely when the accumulator has a negative zero setting, the corresponding positive setting is a series of nines. Under these conditions, if the accumulator were at its positive Zero setting and a unit digit were subtractively entered, this entry would movethe negative setting from a series 'of nin es to a series of zeros giving an erroneous total of zero. Likewise, if the accumulator is at its negative zero setting and a unit digit is additively entered, the positive setting would be changed from a series of nines to a series of Zeros also giving an erroneous total. This error would always occur regardless of the value entries whenever the accumulator passed through a positive or negative zero setting following a change in its direction of operation.

This mechanical inaccuracy in the accumulator is compensated by a fugitive 1 addition mechanism which adds a unit to the lowest order of the accumulator whenever the highest order passes through its 0 position after a change in operational direction. This addition of the fugitive 1 when-a unit digit is added to the accumulator while in its negative Zero position, changes the erroneous zero total to the correct positive "1 total and, when a unit digit is subtracted from the accumulator when in its positive zero position, changes the erroneous zero total to the correct negative 1 total.

The accumulator will thus carry the true total whether the sign be positive or'negative.

The accumulator also includes mechanism which senses the sign of the total value in the accumulator and conditions the associated total taking mechanism to take either a positive or a negative total.

When the total or subtotal control key is depressed, the actuator is drivingly connected with the accumulator through either the positive or negative transmission, depending on the condition of the sign sensing mechanism of the accumulator, and,'upon cycling of the machine by the power cycling mechanism, reads out the total in the accumulator and transfers the total to the printing mechanism which prints it on the associated tape near the middle of the machine cycle.

When the total key is depressed, the actuator is connected to the. accumulator during the advance stroke of the actuator to read out the total in the accumulator and transfer this value to the printing mechanism and is disconnected from the accumulator at the end of the advance stroke of the actuator so that the accumulator is not operated during the return stroke of the actuator but is left in its zero setting or cleared condition. However, when the subtotal key is operated, the actuator is maintained in driving relationship with the accumulator during both the advance stroke and the return stroke of the actuator so that the total value read out of the accumulator on the advance stroke of the actuator is returned to the accumulator on the return stroke of the actuator and further entries are added to or subtracted from this restored total.

The printing mechanism includes symbol printing apparatus which is driven by a special unit of the actuator and power cycling mechanism but controlled by the control keys and accumulator so that it will print the proper symbol for the operation performed and give the proper sign to the symbol. Thus, the following symbols may be used to indicate the different operations and the sign of the quantity printed:

Addition r No symbol Subtraction (Minus sign in negative ribbon color) Subtotal positive S Subtotal-negative S Total-positive T Total-negative -o T Print only"; N

There is also a clear signal printing mechanism which,

upon the next additive, subtractive or print only cycle following a total cycle, prints a clear signal symbol, for examplea C, on the tape to indicate that the accumulator had been cleared before the new entry was made.

' Them-int only key is used when it is desired to print a number, such as an identifying or code number, on the tape without entry of such number as a value into the accumulator. This is accomplished by connecting the selector to the printing mechanism through the positive transmission and actuator during the advance stroke of the actuator and blocking any connection between the actuator and accumulator during the return stroke of the actuator. The control keys are all connectedto the power cycling mechanism in a manner to initiate a cycle or rotation of the power cycling mechanism whenever a control key is operated; The power cycling mechanism is so constructed and arranged that it will automatically complete a full cycle or rotation and come to a stop at a predetermined angular position once a cycle has been initiated by depression of a control key. Blocking means are'also provided a'r'iaae'r so associated with the control keys that only one control key can be operated at a time and no other control key can be operated until after the completion of the cycle initiated by this operated key.

This precludes the possibility of forcing the machine to attempt two or more different operations at the same time and thus avoids probable errors and damage to the machine mechanism.

The machine will thus print positive and negative entries and distinguish between the positive and negative values printed, will accumulate the entry values into positive and negative totals and compensate inherent mechanical errors to provide true total values, will read out and print totals and subtotals and automatically sense the positive or negative nature of such totals, will repeat add the same value any desired number of times, will print numbers without entering such numbers into the accumulator, will clear itself whenever a total is taken but will retain its total when a subtotal is taken, will print appropriate symbols indicating the nature of the entry or the total and can be cleared of an erroneous entry before the entry is printed or accumulated.

Suitable mechanical assemblies for carrying out the above-noted functions of the machine are shown in Figs. 2 to 10, inclusive, to which reference may now be had.

POWER CYCLE MECHANISM The power cycle mechanism of the machine includes an electric motor, not illustrated, mounted in the rear portion of the machine and provided with a suitable normally open switch 139, which, when closed, completes the motor energizing circuit.

1. Speed reducing gear train-Fig. 2

The motor has a shaft 140 projecting through the righthand frame side plates of the machine and carrying at the outer side of the frame plate a small spur gear 141, and a cam shaft 135 is journalled in the right-hand and left-hand frame plates and extends transversely of the machine with its axis in spaced and substantially parallel relationship to the axis of the motor shaft. One end of the cam shaft projects through the right-hand frame plate and a spur gear 142, larger than the gear 141, is journalled on this projecting end of the cam shaft. A first idler gear 143, larger than the gear 141, is journalled on an arbor 144 mounted on the frame plate and meshes with the gear 141 and a gear 145 smaller than gear 143 is journalled on arbor 144 and secured to gear 143. A second idler gear 146, larger than the gears 141 and 145, is journalled on a frame carried arbor 147 and meshes with the small gear 145 and a reversing gear 148, is journalled on a frame carried arbor 149 and meshes with the gears 146 and 142 to complete a speed reducing gear drive between the motor shaft and the cam shaft gear, the direction of rotation of gear 142 being retained the same as the direction of rotation of the motor shaft 141), or ClOCkWiS6,'fiS viewed in Fig. 2. At their outer ends arbors 144 and 149 and shafts 141i and 135 are supported in an outboard bracket secured to and spaced outwardly-from the right-hand frame plate, and indicated at 14'.

2. Single rotation clutchFigs. 2 and 3 A one rotation or single cycle clutch, generally indicated at 151), is connected between the cam shaft gear 142 and the cam shaft 135 and includes a ratchet wheel 151 secured to the gear 142, a ratchet pawl 152 pivoted at one end on a cam plate secured on shaft 135 and having intermediate its length a detent engageable with the teeth of the ratchet Wheel to drivingly connect the gear 142 to the cam shaft 135,

The pawl 152 is urged in a ratchet engaging direction by a spring 153 connected between the gear 142 and the free end of the pawl, and a transverse shoulder 154 is provided on the pawl at the free end thereof. A pawl latch dog 155 is pivoted at one end on the right-hand frame plate by a pivotal mounting 156 and is engageable at its free end with the pawl shoulder 154 to hold the pawl out of engagement with the ratchet wheel 151 under which conditions the motor shaft can rotate the gear 142 without rotating the cam shaft 135. When the latch dog is disengaged from the pawl shoulder 154, the pawl engages the ratchet Wheel and drivingly connects the motor driven gear 142 to the cam shaft for a single complete rotation of the cam shaft, cam shaft rotation being terminated when the pawl shoulder 154 again comes into engagement with the free end of the pawl latch dog and the pawl is moved out of engagement with the ratchet wheel.

The cam disk 157, which carries the pawl 152, is mounted on the cam shaft adjacent the gear 142 and has a circular periphery interrupted by a single dwell 158 of limited angular extent. The latch dog 155 carries a lateraliy projecting roller 159 which rides on the periphery of the cam disk 157 and holds the latch dog 155 out of its pawl engaging position until the cam shaft has com pleted a rotation and returned to its home position at which time the roller 159 drops into the cam dwell 158 and frees the latch dog 155 to engage the pawl shoulder 154. This cam disk 157 also serves to hold a depressed control key down until the end of the operating cycle which was initiated by the depression of the control key, as will be presently described.

A spirally-shaped antibacklash cam disk 160 is mounted on the cam shaft 135 and has a single radially disposed shoulder 161. A pawl 162 is pivotally mounted at one end on frame bracket 14 by a pivotal connection 165 and the free end of this pawl is held in engagement with the periphery of cam disk 160 by a spring 166 connected between the bracket 14 and the distal end of a pawl extension or tail 167. The pawl 162 engages the cam shoulder 161 when the cam shaft is in its home or full-cycle position and precludes any reverse rotation of the cam shaft when the rotation of the cam shaft starts or terminates. v

The clutch pawl latch dog 155 is moved to its pawl releasing position upon operation of a control key of the machine by a link 168 pivotally connected at its rear end to the latch dog 155 and an extension 169 of this link extends rearwardly from the rear end of the link 168 to a connection with the motor switch 139 to energize the motor when the cam shaft clutch is engaged. Forward movement of the link 168 and link extension 169 to engage the clutch and close the motor switch is resiliently resisted by a spring 164.

3. Cam and cam shaft assembly.--Fig. 3

The cam shaft 135, in addition to the clutch control cam disk 157, the antibacklash cam disk 160 and the shiftable selector unit return arm 137 carries at locations spaced apart therealong, machine operating cam disks as illustrated in Fig. 3 and including, from left to right along I the cam shaft, the return arm 137 and arm carried pin 138 for returning the shiftable selector unit to its home position, a pendant gear or shiftable transmission latching cam 170, a zero foil actuating cam 171 for the printing mechanism, a printing cam 172, a tens-carry actuat ing cam 173 for the machine accumulator, an actuator operating trail cam 174, an actuator operating lead cam 175, an actuator sector aligner cam 176, a sub-total cycle cam 177, a total cycle earn 178, and a transmission shifting cam 179.

All of the cams are shown in Fig, 3 in their home or full-cycle position and the cam shaft is iournalled in the frame side plates 134 and 14 and the intermediate frame plates 186 and 187 of the machine.

ACTUATING MECHANISM.FIG. 4

The actuator mechanism (Fig. 4) comprises an axle shaft journalled at its ends in intermediate frame plates of the machine and extending transversely of the machine above and substantially parallel to the cam shaft 135. Actuator sectors 188, equal in number to the num- 7 e: of selec o sect rs plu r iournalled in sideby-side or ordinal arrangement on the axle shaft 185 and extend from the axle shaft toward the shiftable selector unit constituting a portion of the digitation mechanism A.

Each actuator sector is substantially of the shape of a section of a circle and the axis of the axle shaft extends through the centers of the hypothetical circles of which the corresponding sectors constitute sections. Gear teeth 189 are provided on the arcuate edges of the actuator sectors and each sector is provided with an elongated opening 190 having'a longitudinal curvature centered on the axis of shaft 185. The sectors may also be provided with weight reducing openings.

A rod or bail 192 extends through the openings 19%) in the several actuator sectors and arms 193 and 19 1, as shown in Fig. 5, connected between the corresponding ends of the bail 192 and the shaft 135 near the correspondingly opposite ends of this shaft support the bail 192 in spaced and parallel relationship to the axle shaft 135.

A yoke 195 of somewhat elliptical shape, shown in Fig. 5, surrounds the cam shaft 135 and the actuator trail and lead cams 174 and 175 and has an upwardly and forwardly projecting extension pivotally mounted on a fixed cam follower shaft 196 which extends transversely of the machine above and forwardly of the cam shaft 135 and is supported in the side and intermediate plates of the machine frame. An arm 197 extends forwardly from the extension 195 and is pivotally connected by a spacing pin 198 to the distal end of one leg 1% of a ribbon feed actuating bellcrank lever 205i rockably mounted on the cam follower supporting shaft 196. The other leg 2% of bellcrank lever 200 extends upwardly from shaft 196 and is connected at its upper end to the forward end of a link 292 which drives the ribbonfeed of the printing mechanism, presently to bedescribecl.

An arm 263 extends rearwardly from the rearward end of the yoke 194 and is pivotally connected at its rearward or distal end to the lower end of a link 2&4, the upper end of which is connected to the actuator bail 192.

The yoke carries on its upper side a cam following roller 205 riding on the peripheral edge of the actuator trail cam 174 and on its lower side a cam following roller 206 riding on the peripheral edge of the actuator lead earn 175, the yoke being disposed betwen the cams 17d and 175 and the roller 205 projecting from the right-hand side of the yoke while the roller 206 projects from the lefthand side of the yoke.

With this arrangement the bail 192 is positively moved both downwardly and upwardly and, during an operating cycle of the machine, is first moved to its lower position, is maintained in its lower position for a predetermined time intervaland is then restored to its upper position.

A corresponding latch lever 208 (Fig. 4) is disposed adjacent one side. of each actuator sector and is pivoted at its upper end to the sector near the upper radial edge of the sector by a pivotal connection 2% and extends from the pivotal connection along the opening 1% in the actuator sector and past the side of the bail remote from the axle shaft 135. The latch lever angularly bent intermediate its length to provide at the side thereof adjacent the bail 192 a con-cave seat 219 which receives a roller 21% rotatably mounted on the bail 192, the roller 21% being received in the correspond ing seat 2143 when the bail'is in its upper limiting positi n relative to the corresponding sector 138. The latch lever is resiliently held in engagement with the bail by a spring 211 connected between the sector 138 and the distal end of an arm 212 projecting angularly from the pivoted end of the lever 208. The portion of the lever 2% between the seat 21(Band the free end of the latch lever constitutes a longitudinally curved tail portion 213 directed from the bail 192 toward the shaft185.

Whenthe bail is. pulled downwardly by the action of the lead cam lflS onthe camfollower 2%, the engagement of the bail in the latch lever seat 210 pulls the sector 138 down until the sector is positively stopped at an angu lar position predetermined by the setting of a corresponduntil the bail positively engages the sector and returns it upwardly to its home or full-cycle position, the bail being moved upwardly by the action of trail cam- 174 on follower 205.

The actuator unit is fixedly mounted in the machine just to the left of the shiftable selector unit when the latter is in its right-hand, home position and, when the selector unit is stepped to the left by its escapement mechanism, the orders of the selector unit from left to right are successively brought into alignment with the corresponding orders of the actuator mechanism from right to left. Thus the digits carried by orders in the left-hand end portion of the selector will be read out by corresponding orders in the right-hand end portion of the actuator unit.

When the bail 192 moves upwardly relative to the actuator sectors 138, it comes into engagement with abutment formations 214 at the upper ends of the openings 355 h in the sectors, simultaneously moving into the seats 21o of the latch levers 203, and then moves the actuator sectors upwardly until the upper radial edges of the sectors abut against a stop bar 215 in the upper or full-cycle position of the actuator sectors.

PRINTING MECHANISM 1. Print wheels and gear mechanism-Fig. 4

The printing mechanism, generally indicated at 216, is disposed above the actuator mechanism with its orders in alignment with corresponding orders of the actuator mechanism. A plurality of print wheel drive gears 217 are journalled on a drive gear shaft 218 which extends transversely of the machine above and parallel to the cam shaft 135 and is mounted at its ends in the intermediate frame plates 186 and 187. The gears 217 are disposed in side-by-side or ordinal arrangement along the shaft 218 and the number of the gears is equal. to the number of actuator sectors 188. Each gear 217 includes a central hub portion 219 of cylindrical shape provided with a peripheral notch 220 the purpose of which will presently be explained.

A plurality of print wheel carriers 221 are rockably mounted intermediate their length on a fixed shaft 222 which extends transversely of the machine in spaced and parallel relationship to the shaft 218. Each carrier 221 includes a pair of parallel arms 223 and 224 with the pairs of arms arranged in side-by-side or ordinal arrangement along the shaft 222 and in alignment with corresponding drive gears 217 and actuator sectors 188. Both arms 223: and 224 extend upwardly from the shaft 222 and near the upper end of the arm 224, a pivot pin or axle 225 extends transversely through the two arms of: each pair and carries an idler gear 226 which meshes with the corresponding drive gear 217. The arm 223 of the carrier pair 221 is extended upwardly and forwardly beyond the upper end of the arm 224 and carries an axle pin 22? spaced above the axle pin 225. A print wheel gear 231) is journalled on the axle pin 227 and includes a spur gear portion 231 the teeth of which mesh with the teeth of the idler gear 226 mounted in the same carrier and which is formed on one side of a print wheel portion 232 having printing bosses 233 projecting from the periphery thereof at uniformly spaced angular intervals there-around. It will be noted that the printing bosses 233 are spaced apart and; that the outer surfaces of these bosses are made concave in 2. Zero foil latch mechanism-Fig. 4

Each of the arms 223 is provided with an extension 235 directed forwardly from the pivot shaft 222 and overlying one side of the outer portion of the corresponding drive gear 217 to serve as a guide for maintaining the corresponding drive gears 217 and idler gears 226 in meshing alignment with each other. The arm 223 is also extended forwardly of the print wheel axle pin 227, as indicated at 236, and this forward extension is notched out to provide at its lower portion a latch shoulder 237 facing upwardly and forwardly. A plurality of irregularly-shaped zero foil latch levers 238, equal in number to the number of print wheel drive gears 217 and print wheel carriers 221, are pivotally mounted intermediate their length on a fixed shaft 239 which extends transversely of the machine in spaced and parallel relationship to shafts 218 and 222. Each of these Zero foil latch levers 238 has an upwardly directed arm 24% provided at its upper end with a rearwardly directed detent formation 241 which engages the shoulder 237 on the corresponding print wheel carrier arm 223 to releasably latch the corresponding print wheel in nonprinting position in which it is spaced from the associated printing platen 242. The latch levers 238 are received in corresponding transverse notches or recesses in a comb bar 243 which extends transversely of the machine above and parallel to the shaft 239 to maintain these latch levers in properly spaced relationship to each other and each lever has a forwardly directed lever arm 244 and a rearwardly directed arm 245, the rear end portion of which is disposed against the same side of the corresponding drive gear 217 against which the forward extension 235 of the carrier arm 223 is disposed. A spring 246 is connected between the distal end of each forwardly directed latch lever arm 244 and a fixed spring attaching bar 247 extending transversely of the machine above and substantially parallel to the shaft 239, these springs urging the corresponding latch levers to rock in a clockwise direction as illustrated in Fig. 4. Each rearwardly directed latch bar arm 245 has on its rearward end a downwardly directed detent 248 which drops into the notch 220 in the corresponding print drive gear wheel hub 219 to free the latch arm for clockwise rocking movement by the associated spring 246 to a position in which the latching detent 241 at the upper end of the upwardly directed arm 240 of the latch lever engages over the corresponding shoulder 237 on the carrier arm 223.

A latch releasing bail 250 extends through slots, as indicated at 251, in the intermediate frame plates 186 and 187 and across the upper edges of the forwardly directed arms 244 of the latch levers 238. The bail 250 is supported at its ends in the upper ends of a pair of arms, one of which is illustrated in Fig. 6 and designated at 252, pivotally mounted at locations spaced below the bail 250 on the intermediate frame plates 186 and 187, as indicated at 253 for the arm 252 so that the bail 250 can swing forwardly and downwardly and upwardly and rearwardly in the slots 2 51,

The arm 252, as shown in Fig. 6., is extended downward? ly beyond its pivotal mounting 253 upon the intermediate frame plate 187 and is provided at its lower end with a laterally projectihg abutment pin 254. A cam follower lever 255 is pivotally mounted intermediate its length on the transverse shaft 196 and has on its upper end a formation 256, in engagement with the forward side of the abutment pin 254. At its lower end the lever 255 carries a cam following roller 257 which rides on the peripheral edge of the zero foil cam 171 mounted on the cam shaft 135. The zero foil cam 171 is so shaped that during approximately the first 180 degrees of a machine cycle, during which time the actuator sectors 188 are undergoing their downward stroke, the bail 250 is held down on the forwardly directed arms 244 of the latch levers 238 holding the latch lever detents 241 out of engagement with the latching shoulders 237 on the print wheel carrier arms 223. This maintains the latch lever detents 248 out of the notches 220 in the print Wheel drive gear hubs 219 and frees the drive gears for rotational movement. Near the end of the first half and beginning of the second half of the machine cycle, while the actuator sectors are being held in their limiting downward positions, the cam follower 257 rides into a dwell of the cam 171 and a tension spring 260 connected between the upper end of the bail support ing arm 252 and the machine frame raises the latch lever bail 25% away from the latch lever arms 244 and thereby conditions the latch levers to move into engagement with the corresponding shoulders 237 under the actuation of the corresponding latch lever springs 246.

During the downward stroke of the actuator sectors and while the latch levers 238 are held out of engagement with the notches 229 in the drive gear hubs 219 by the bail 2513, those drive gears in alignment with selector sectors which have been manually set to numeral values will be rotated away from their 0 positions in a manner presently to be described, so that, when the actuator bail 192 approaches the end of its downward movement and the bail 250 is moved to release the latch levers 238, the notches in the drive gears, which have been rotated from the 0 positions will be moved out of registry with the corresponding zero foil latch lever detents. 248 and these detents will not be able to re-enter the corresponding notches 220 and will be held on the cylindrical peripheral surfaces of the corresponding hub formations 219 so that the corresponding latch lever abutments 241 will be held out of engagement with the shoulders 237 of the corresponding print wheel carriers 221 leaving these carriers free to rock the print wheels 230 carried thereby toward the platen 242 during the printing operation, presently to be described.

The upwardly directed arm 24% of each latch lever 238 has near its upward end a forwardly directed projection 261 the outer end portion of which is laterally directed to the left, as viewed from the front of the machine, and overlies the outer end of the projection 261 on the next latch lever to the left, these forward extensions being omitted from the upwardly projecting arms of the first two latch levers at the right-hand end of the assembly, The arrangement is such that if any print wheel drive gear to the left of the first two gears at the right-hand end of the assembly is moved away from its 0 position, all of the latch levers to the right of such drive gear will be held by the zero foil profiections 261 out of latching engagement with the corresponding shoulders 237 on the print wheel carrier arms 223 and the print wheels to the right of the indicated drive gear will be free to move in a printing operation. Since-the drive gears to the left of the indicated drive gear have not been moved and still have their hub notches 226 in registry with the zero foil latch lever detents 248 and since the latch levers to the left are not restrained by the projections 261, these latch levers to the left of the indicated drive gear will be moved by their springs 251 into latching engagement with the corresponding shoulders 237 to hold the corresponding print wheels against printing movement so that the printing mechanism will not print Zeros to the left of the highest order of the numeral entry made into the machine by the keyboard and selection mechanism as previously explained.

When the actuator sectors have been returned to their upward position at the end of the machine: cycle, the bail 250 will have been moved downwardly by the cam 171 to raise all of the latch lever detents 248 out of the corresponding notches 220 in the print drive gear hubs 2 19 thereby freeing the print wheel drive gears for rotational movement by the downward stroke of the actuator sectors during the first portion of the next. operating cycle 3. Printing 0perati0n-Fig. 4

The lever arm 224 of each print wheel carrier 221 is provided with a rearwardly directed extension or tail portion 263 and a tension spring 264 is connected between the rear end of each rearward extension 263 and the machine frame, and is effective, when released, to rock the corresponding print wheel carrier 221 about the shaft 222 in a direction such that the associated print Filed 23% is moved rearwardly to strike the adjacent, forward portion of the cylindrical surface of the platen 242.

A bail cross member in the form of a rod 265 extends transversely of the machine below the rearward extensions 263 of the carrier levers 224 and is supported at its ends in the rearward ends of a pair of bail supporting arms 266 and 267, as shown in Figs. 4, 7 and 8. At their forward ends the arms 266 and 267 are pivotally mounted on the carrier supporting shaft 222 and the arm 266 is provided at a location spaced somewhat above and forwardly of the bail 265 with a laterally projecting stud 263 which preferably carries a sleeve or roller 269.

A bellcrank lever 279 (Fig. 8) is pivotally mounted at its knee on the axle shaft 218 of the print wheel drive gears 217 and has the rearward or distal end of one of its arms 271 underlying the stud carried roller 269. The other arm 272 of this bellcrank lever extends downwardly and rearwardly from the shaft 218 and to a location opposite the cam shaft 135 and carries on its lower or distal end a cam following roller 273 which rides on the peripheral edge of the print earn 172.

The print cam 172 is so shaped that during the major portion of a machine cycle the bail 265 is supported in its upper limiting position in which it holds the lever extensions 263 upwardly and renders the springs 26% ineffective to move the print wheels 23% toward the platen 242. The cam 172 is provided with a dwell 27d of restricted angular extent into which the cam follower 273 drops during a time interval in which the actuator sectors 138 are retained at the end of their downward stroke, as described above, momentarily moving the bail 263 downwardly away from the bottom edges of the carrier lever extensions 263 and conditioning the springs 264 to rock the carriers 228 which have been freed from their as sociated latch levers 238 in a direction to strike the print wheels 2315 against the platen 242. After the free print wheels have been moved to stroke the platen 242, they are immediately returned to their home or full-cycle positron by reason of the limited angular extent of the dwell 274 in the printing cam 172.

A portion of the arm 223 of each print wheel carrier 221 is perpendicularly offset from the edge of the arm and arcuately curved longitudinally to overlie the portion of the corresponding idler gear 226 nearest the platen 242 to provide a dust shield 275 for the idler gear.

When a print wheel carriage 221 is rocked about the shaft 222 to move the corresponding print wheel 231) from its home or full-cycle position to its platen engaging position, the teeth of the corresponding idler gear 226 are moved out of mesh with the teeth of the associated print wheel drive gear 217, although they remain in mesh with the teeth of the associated print wheel gear 231.

This unmeshing of the idler gear 226 and the drive gear 217 would leave the print wheel free to turn while it is positioned near the platen 242 if some means were not provided to lock the print wheel in its rotational position during this printing movement of the print wheel.

A print wheel locking pawl 2'78 (Fig. 4) is pivotally mounted intermediate its length on each print wheel carried arm 221 by a pivotal connection 279 disposed for.- wardly of and somewhat below the corresponding print wheel axle pin 227. The locking pawl 278 is disposed in substantially upright position at the forward side of the associated print wheel and has on its upper end a hook formation 28% the end of which is double beveled to fit between any two adjacent printing bosses 233 projecting from the periphery of the associated print wheel. A tension spring 281 is connected between the lower end of the locking pawl 278 and the forward extension 236 of the arm 223 below the shoulder 237 and resiliently urges the locking pawl to rock about the pivotal mounting 279 in a direction to engage the end of the hook formation 28% thereof between adjacent printing bosses on the print wheel. At its lower end the pawl 278 is provided with a notch 282 of inverted V-shape and an actuating bar 2&3 extends transversely of the machine through the notches in the lower ends of all of the print wheel locking pawls 273.

The pawl actuating bar 283 is disposed in spaced parallel relationship to the drive gear axle 2'17 and is carried at its endson the distal ends of the legs 284 and 285 of a reetangularly-shaped bail zss pivotally mounted on the axle shaft 218 and near the intermediate or cross portion 287 of the bail.

A cam following rocker arm 290 (Fig. 5) is pivotally mounted intermediate its length on the drive gear axle shaft 218 at the outer side of the intermediate frame member 186 and is disposed in substantially upright position. A cam following roller 291 on the bottom end of the arm 2% rides on the peripheral edge of the tenstransfer cam 173 at the forward side of this cam and a tension spring 292-. connected between the upper end of the rocker arm 290 and the. machine frame resiliently holds the cam following roller against the associated earn 173. A spacing pin 293 extending through a slot in the intermediate frame plate 186 connects the rocker arm 290 above the shaft 218 to the leg 285 of the bail 286 and a second spacing pin 294 connects a forward extension of the rocker arm 2% to the forward portion of the leg 285 of the bail 286.

The shape of the tens-transfer control earn 173 is such that the spring 292, which holds roller 291 against the peripheral edge of this cam, will hold the actuating bar 2%3 in such position, as illustrated in Fig. 4, relative to the lower ends of the locking pawls 278, that the pawls will be held. out of engagement with the corresponding printing wheels until the actuator bail 192 nears the end of its downward stroke. At this time the roller 291 rides off of the lobe 295 of the earn 173 and frees the spring 292 to move the bar 283 in a direction to free the'springs 281 to force the ends of the hook formations at the outer ends of the locking pawls 273 into engagement between the angularly spaced-apart printing bosses of the associated printing wheels. At the same time the actuator sectors are aligned and latched in position by means presently described, and immediately afterward the print control bail 265 is moved to free the springs 264 to swing the released print wheel carrying arms 221. As the print wheel carrying arms are swung, the print wheel idler gears 226 are moved out of mesh with the print wheel drive gears 217, but, as the idler gears are held against rotation by erngagement of the pawls 278 with the print wheels and the actuator sectors and print wheel drive gears are latched against rotation, no relative rotation between the idler gears 226 and drive gears 217 takes place during printing. The print wheels are also held firmly against rotational movement during the printing movement of the print wheel carrying arms.

When the printing operation has been completed and the print control bail 265 moved upwardly to restore the pnnt wheel carrying arms 221 to their full-cycle position, a pin 29.6 on the actuator lead cam 175 engages an offset shoulder 297 near the lower end of arm 298 and rocks this arm back to the full-cycle position shown in Fig. 4-, thereby moving the pawls 278 out of engagement with the print wheels and restoring the rotational freedom of the print wheels so that the print wheels which have been moved away from their position can be restored to their 0 position on the upward stroke of the actuator bail 192. Shortly after the pin 296 has restored the arm 2% the roller 291 again rides onto the lobe of cam 173 and the arm holds the bar 283 in position to maintain the pawls 278 clear of the print wheels 23d until the next printing operation.

The pawls 278 are thus positively moved in both directions by the rod 283 acting against the sides of the V- shaped notches 282 in the pawls, the rod 2% being power actuated in timed relationship to machine operation by earn 173 and spring 292.

POSITIVE TRANSMISSION GEAR MECHANISM- FIG. 8

The mechanism, as mentioned above, which drivingly connects the actuator sectors 188 to the selector sectors 33, comprises a positive transmission gear mechanism disposed between the actuator and selector sectors and generally indicated at 330 in Fig. 8. This gear mechanism 330 comprises a bail including parallel legs, as indicated at 331 in Fig. 8, spaced apart a distance somewhat greater than the length of the actuator mechanism and interconnected by a suitable cross member 332 and the gear shafts 334, 335 and 336. A top cross member or transmission shifting member 33 (Fig. 7) ex tends perpendicularly from the upper end of one leg above the top gear shaft and is used to shift the positive gear transmission mechanism, as will later appear.

The bail provides a rigid cage or carriage for the transmission gears and the three gear shafts or axles 33 i, 335, and 336 extend transversely of the space between the bail legs 331 in spaced-apart and parallel relationship to each other and are mounted at their ends the corresponding bail legs at locations spaced apart longitudinally of the legs. A plurality of transmission gears 337 (Fig. 4) are journalled on the upper gear shaft 334 in side-by-side or ordinal arrangement, the number of these gears being equal to the number of actuator sectors 183 and the gears being constantly in mesh with the corresponding actuator sectors and with the corresponding print wheel drive gears 217, as is shown in Fig. 4. A plurality of intermediate or reversing gears are journalled in side-by-side or ordinal arrangement on the intermediate gear axle 335 and these gears mesh respectively with the gears 337. A plurality of gears are also journalled on the gear axle 336 in side-by-side or ordinal arrangement, the number of these gears also being the same as the number of selector sectors and these gears mesh with the corresponding intermediate or reversing gears. The transmission gears are preferably all tentooth gears of the same size with teeth of the size of the teeth on the selector sectors and on the actuator sectors 1&8.

The upper gear axle 334 is extended beyond the legs of the gear carrying cage and is mounted at its ends in the intermediate frame plates of the machine so that the entire cage can swing about the axis of the axle 334 carrying with it the gear axles 335 and 336 and the corresponding gears.

Tn the addition and substraction cycles of the machine, the cage of the positive transmission mechanism is rocked by the cam 179 in a manner to bring transmission gears on axle 336, corresponding in number to the number of activated selector sectors, into mesh with the corresponding selector sectors during the first portion of the machine cycle in which the actuator segment bail 192 is given its downward stroke. During the downward stroke of the actuator hail, the actuator segments in alignment with the selector segments, which have been manually set and which are engaged or meshed with corresponding positive transmission gears will be returned to their home or 0 position. During the downward movement of the corresponding actuator sectors, the print wheels 230 in alignment with these sectors are rotated by the corresponding gears 337, 217 and 226 to bring the numerals embossed on the printlwheels, which correspond to the numbers for which the corresponding selector sectors are set in position, to impinge the platen 242 during the printing movement of the print wheels, as described above.

In an additive or subtractive operating cycle of the machine and during the downward movement of the actuator sectors in mesh with corresponding selector sectors, these actuator sectors will have moved the cor responding print wheels through the gear trains including the corresponding positive transmission gears 337, the print wheel drive gears 217 and the print wheel idler gears 226, so that the print wheels will be set for printing the value which has been entered into the digitation mechanism, as described above, the print wheels to the left of those which have been rotated to printing position by the corresponding selector sectors being held in nonprinting position by the zero foil mechanism previously described. Also, when the actuator bail reaches the end of its downward movement the d-ifierentially set selector sectors will have been returned to their 0 position and latched in this position by their zero latches.

After the print wheels have been brought to proper printing position and the actuator sectors locked in position to hold the print wheels against rotational movement, the printing bail 265 is dropped by action of the cam 172 on the cam following bellcrank lever 270, as shown in Fig. 8, thereby permitting the print wheels which have been unlatched by rotation of the associated print wheel drive gears 216 to strike the platen 242 and print the value on the paper tape carried around the platen. The actuator sectors are now released and the trail cam 174 acts on the cam follower 205 carried by the yoke to return the actuator bail 192 to its uppermost position, the upward movement of this bail returning all of the actuator sectors upwardly to their home or full-cycle position, as previously described.

This upward movement of the actuator sectors turns the print wheels which have been moved away from their zero setting back to their zero setting and also enters the entry value carried by the selector sectors and now determined by the positioning of the actuator sectors away from their home or full-cycle position into the accumulator. During the upward stroke of the actuator sectors the print wheels are restored to the 0 position.

The entry value has now been printed and entered into the accumulator and the machine has been returned to its normal or full-cycle position.

RIBBON MECHANISM J Ribbon supporting and feeding mechanism An inked ribbon extends through the space between the printing wheels 230 and the platen 242 and is disposed adjacent the platen. This ribbon is wound at its ends on spaced-apart ribbon spools, one of which is illustrated in Fig. 9 and indicated at 762, disposed at respectively opposite sides of the printing mechanism and supported on corresponding brackets, as indicated at 763, mounted on and projecting inwardly from the left-hand intermediate frame plate 134 and the righthand frame plate 14, the spools being mounted for rota tion about substantially vertical axes and the ribbon being securely attached at its ends to the corresponding spools.

A ratchet wheel 764 is disposed at the bottom of each ribbon spool concentric with the axis of spool rotation and drivingly connected to the corresponding spool, and a rocking or oscillating plate 765 is disposed immediately below each ratchet wheel and pivotally mounted on the bracket carried pin 766 on which the corresponding spool and ratchet wheel are rotatably mounted. Each 15 rocking. plate 765 has a forwardly directed. arm 767 and. these arms are interconnected at their forward or distal. ends by a cross link 768 so that both plates 765 oscillate about the corresponding pins 766 simultaneously and coextensively.

Each plate 765 also has a rearwardly directed arm 7 d9 terminating in an upwardly directed tongue 77:) disposed substantially tangential to and spaced from the tooth periphery of the associated ratchet wheel 76 The left-hand plate 765 is also provided with an arm 771 of angular shape having an inner portion 772 directed outwardly to the rightv from the portion of the left-hand plate 765 through which the pin 766 extends and an outer portion 773 directed rearwardly from the outer end of the portion 772. A link 774 is pivotally connected at its forward end to the rearward end of the arm portion 773 and extends rearwardly from the arm 771, this link being provided at its rearward end with a formation 775 having a pair of elongated notches 776 and 777 extending diver-gently to the left from the right-hand edge of the formation 775 and having a common opening through the right-hand edge of the formation, and a tongue 7'73 extending to the left with its center line substantially perpendicular to the longitudinal center line of the link 774 and carrying near its distal or left-hand end an upwardly directed stud 779.

An upright lever 78%, as shown in Fig. 5, is pivotally mounted at its lower end on a stud 7S1 carried by and projecting to the right from the left-hand frame plate 134 immediately below the actuator sector axle shaft 385 and this lever carries on its upper end an upstanding pin v 782 which extends through the notches 776 and 777 in the rear end portion of the link 774. An abutment formation 783 is mounted on the upper end of the lever 784. and bears against the underside of the link 774 to support the link, and an abutment washer 784 is mounted on the pin 782 above the link 77 4. A tension spring 7% is connected between the upper end portion of the pin 782 and the tongue carried stud 779 and resiliently maintains the pin in one or the other of the notches 776 or 777, as will later appear.

' The link 202 (Fig. 5) pivotally connected at its forward end to the upper end of the arm 261 of the bellcrank lever 20%) mounted on the shaft 1% and connected by the spacing pin 198 to the actuator bail operating yoke l 195, as previously described, is pivotally connected at its rearward end to the lever 7% intermediate the length of this lever to impart a forward and rearward rocking movement to the lever 78 each time the cam shaft 135 rotates. lever 780, by reason of engagement of the lever carried pin 782 in one of the notches 776 or 777 in the rear end portion 775 of the link 7.74 imparts an oscillating movement to the rocker plates 765 each time the machine cam shaft rotates.

An actuating pawl 787 (Fig. 9) is pivotally mounted near one end on the plate 765 at the forward side of the ratchet wheel 764, as indicated at 788, and has at one end a detent 789 which engages with the teeth of the ratchet wheel to turn the ratchet wheel incident to the angular movement in one direction of the plate 765. A spring 790 connected between the distal end of a forwardly extending tail portion 791 of the pawl 787 and a stud 792 mounted on the plate arm 767 resiliently urges the pawl detent 789 into engagement with the ratchet teeth of the corresponding ratchet wheel.

I t is understood that a similar actuating pawl is mounted on the right-hand oscillating plate and is cngageable with the corresponding ratchet wheel, the pawls being so directed as to rotate their corresponding wheels in respectively opposite directions in order to wind the ribbon from either ribbon spool onto the alternative ribbon spool.

A tongue 7% is directed upwardly mm the bracket 763 and tangential to the tooth periphery of the ratchet wheel 76 and a holding pawl 795 is pivotally mounted This fore and aft rocking movement of the at one end by a pin 796 on the bracket 763 and has in termediate its length a detent 797 which engages with the teeth of the ratchet wheel. 764 to hold the ratchet wheel against back rotation while the ratchet wheel is being rotated in a forward direction by the actuating pawl 787 upon oscillating movement of the plate 765. The holding pawl 795 has near its free end a cammed edge 798 opposed to the adjacent edge of the tongue 77ft upstanding from the arm 769 of the plate 764 and a tension spring 7% is connected between the free end of the holding pawl 795 and a rearwardly projecting tongue 8% of the bracket 763 to resiliently urge the holding pawl in a direction to maintain its detent 797 in engagement with the teeth of the ratchet wheel 764.

When the pin 782 on the upper end of lever 78%? is in the notch 777 nearest the plate arm 771, as shown in Fig. 9, the tongue 770 is maintained out of engagement with the holding pawl 795 and the actuating pawl 7557 is held out of engagement with the bracket tongue 7%. Under these conditions, oscillation of the rocking plate 755' will turn the ratchet wheel 764 in a counter-clockwise direction, as viewed in Fig. 9, to wind the ribbon onto the left-hand spool 762 and off of the right-hand spool.

When the ribbon has been fully wound onto the spool 762, the attachment of the right-hand spool to the corresponding end of the ribbon places a resistance to rotation of the spool 762 which causes the pin 782 to cam over the rounded extension 861 between the slots 776 and 777 and to become engaged in the slot 776, the spring '7 55 providingthe necessary resiliently resisted movement of the pin 732 for this purpose. When the pin 732 is moved into the slot 776 remote from the plate arm 772, the rocking plate 765 is given a clockwise angular movement, as viewed in Fig. 9, which moves the plate carried tongue 770 against the free end of the holding pawl 795 and holds this pawl out of engagement with the teeth of the ratchet wheel 764 and simultaneously moves the actuating pawl 787 against the bracket carried tongues 794 to also hold the actuating pawl out of engagement with the ratchet wheel teeth. This frees the left-hand ratchet wheel 764 and the associated ribbon spool 762 for free rotation and, since the angular movement of the plate 765 is transmitted through the link 765 to the right-hand rocking plate, the holding pawl and actuating pawl of the right-hand mechanism will be moved into operative engagement with the right-hand ratchet wheel and rotation of the right-hand ratchet wheel and righ hand ribbon spool will be eifected to wind the ribbon back from the left-hand to the right-hand spool.

When the ribbon has been wound back onto the righthand spool, resistance to rotation of this spool by reason of the pull of the ribbon on the left-hand spool will force the pin 782 back into the notch 777 and effect the release of the right-hand spool and re-engagement of the lcfthand actuating pawl and holding pawl with the lefthand ratchet wheel 764 to wind the ribbon back onto the lefthand spool.

The ribbon will thus be automatically wound back and forth between the left-hand and right-hand spools as it is fed longitudinally during the printing operations of the machine.

2. Ribbon shifting mechanism The ribbon is medially divided into longitudinal halves of different colors, the top half, for example, being black while the bottom half is red, and the black upper halt of the ribbon is used for printing values additively entered into the machine and positive totals and subtotals and print only figures while the red bottom half of the ribbon is used for printing values subtractively entered into the machine and negative totals and Subtotals. This requires that whenever a quantity is subtractively entered or a negative total or subtotal is taken, the ribbon he s ifted upwardly to place its lower portion in printing position. Suitable ribbon shifting means are shown in Figs. 5 and 7 and comprise left and right-hand arms 8% and 806 mounted on a supporting shaft 807 extending transversely of the machine above and parallel to the actuator bail supporting shaft 185 and supported by the intermediate frame plates 186 and 187.

The arms 805 and 806 are forwardly directed from the shaft 807 and a left-hand arm 803 is pivotally connected at its lower end to the forward end of the arm 805 and extends upwardly from the arm 805 past the ion ward side of the ribbon while a similar arm 8&9 is pivotally connected at its lower end to the forward end of the right-hand arm 806 and extends upwardly from the arm 866 past the forward side of the ribbon. Near their upper ends, the arms 8% and 8&9 are provide with longitudinally extending slots 810 and 812, respectively, which slidably receive corresponding guide studs 8l3'and 814 which are fixedtothe machine frame and guide the arms 808 and 809 in their up-and-down movements.

The arms W8 and 869 have straight longitudinal rearward edges at their upper ends and carry spring clips 317 and 818, respectively, which extend along these straight, rear edge portions and at the rearward side of the ribbon so that the ribbon is slidably held between the spring clips and the adjacent rearward edge portions of the ribbon shifting arms 808 and 809.

A cam 820 is mounted on the actuator bail shaft 185 near the right-hand end of this shaft and has an upwardly extending lobe 821 and a rearwardly directed extension S22 carrying a laterally projecting pin 823 spaced from the shaft 185. A lever 825 is mounted on the shaft 307 at the inner or left-hand side of the arm 8G6 and has three angularly spaced-apart arms including a forwardly directed arm 826, a downwardly and rearwardly directed arm 827 and a downwardlyand forwardly directed arm 82$ carrying near its distal end a cam following roller "829 riding on the edge of the cam lobedZl.

Whenever the .actuator bail 12 is moved downwardly, the cam S20 is rocked in a counter-clockwise direction, as shown in .Fig. 7, imparting a clockwise rotational movement to the lever 825 and this clockwise movement of the lever 325 is resiliently resisted by a tension spring 839 connected between a stud near the distal end of the lever arm 327 and a tie rod 83]. extending transversely of the machine above and rearwardly of the actuator bail shaft 185. a

The right-hand arm 8% has a rearwardly and upwardly directed tail formation 832 carryingnear its distal end a stud 833 connected by a tension spring 834 to a stud 835 carried by the lever arm 827 near thestud $36 to which the lower end of the spring 830 is connected.

Withthis arrangement, whenever the actuator bail is moved downwardly imparting a clockwise rotational movement ot the lever 325, the spring 834 is stretched and resiliently urges the lever arms 8%" and 8% to swing in a clockwise direction, as viewed in Fig. 7, and move the ribbon shifting arms 8% and Siifiupwardly to bring the lower half of the ribbon to printing position.

An elongated lever 337 is pivotally mounted intermediate its length on the right-hand end portion of the mounting shaft 427 of the negative transmission ,gear mechanism 42ll-and is longitudinally bent so that its portion above the shaft 427 is substantially upwardly di rected and its portion below the shaft 427 is downwardly and forwardly directed. At its upper end the lever 435 .is disposed alongside the lever arm 8% and is provided at its upper end with .a forwardly directed hook formation 833 which overlies a stud339 mounted on andextendingtlaterally from the lever arm 53% near the distal end of this lever arm. The hook 833 engages the stud ,A bellcrank lever 840 is pivotally mounted on a shaft of the link 353.

extending transversely of the machine near the rear end of the keyboard and has its.forward end engagedby the subtraction key of the machine in a manner such that the bellcrank lever will be rocked in a counter-clockwise direction, as .viewed in Fig. 7, whenever the subtraction key is manually depressed. The lever 344 also has a rearwardly directed arm provided at its rearward end with a laterally directed hook formation 845 which is opposed to the rearward edge of the lower end portion of the lever 837 so that, when the subtraction key is manually depressed, the lever 837 is rocked by the bellcrank lever 849 in a clockwise direction, as viewed in Fig. 7, to displace the hook formation 838 on the upper end of the lever 837 from the stud 839 and free the ribbon shifting rnehanism for upward movement when the spring 834 is stretched by movement of the arm 327 incident to rotation of the cam SZtl on the actuator bail shaft 185. Thus, a value subtractively entered into the machine will be printed a different color from a value additively entered. V t

The arm 826 of the lever 825 has on its distal end a detent formation 848 which overlies the forward portion of the upper edge of the lever arm 8&6 and engages this arm so that the spring 330 in resiliently rocking the lever 825 in a counter-clockwise direction, as viewed in Fi g. 7, also rocks the arms 305 and $06 in the same direction, urging the arms 8% and W9 downwardly to place the ribbon in position for printingpositive values.

For a more detailed illustration and descriptionof the ribbon feed and shift mechanism reference may be had to application S. N. 369,204, filed July 20, 1953, by Nathaniel F. Hawthorne for Adding Machinej now U. S.

Patent No. 2,732,924.

TAPE FEED MECHANISM FIG. 7

A ratchet wheel 850 is mounted on the platen shaft 851 at the right-hand end of the platen and drivingly connected to the platen anda link 853 is pivotallyconnected at its lower end to the pm 823 ca-rriedby the extension 822 of the ribbon feed cam 820, and this link is upwardly and forwardly directed and provided at its upper end with a forwardly oflfset portion terminating in a pawl detent 854 which is elf ective to engage the teeth of the formation 858, the straight rearward edge of which is opposed to a stud 359 mounted on and projecting to the left from the link 853'near the upper end of this link. The lever 855 has two operativepositions in one of which it' holds the pawl detent d away from the adjacent portion of the ratchet wheel a distance such that the pawl will step only a single ratchet tooth for each upand-down movement of the link 5553 and the platen Will thus be rotated through an angular distance corresponding to one tooth ot the ratchet-85h for each; operating cycle of the machine, and in' the other of which the pawl detent 854 is positioned to engage alternate teeth of the ratchet wheel so that thejplaten will be rotated an angular distancecorresponding to two adjacent teeth of the ratchet wheel foreach up-and-down movement "The lever ass and extend forwardly from the stud $56 and has at its forward end a laterally projecting stud which rests on the upper edge of a total and subillustrated, which extends upwardly from the portion of the lever 855 mounted on the stud 856 and a portion of the machine frame disposed forwardly of the arm 861. When the machine is put into its total or subtotal cycle, the front end of lever 885, is raised and the foot 858 lowered so that the link 853 will double space the platen 242 at the end of such a cycle.

A guide link 863 for the link 853 is pivotally mounted at one end on a stud 864 projecting to the right from the right-hand intermediate frame plate 187 and the guide link 863 depends from the stud 864 and has therein a longitudinally extending slot 865 below the stud 864 receiving a stud 866 projecting laterally from the link 853. A tension spring 867 connected between the link 853 and the adjacent frame plate resiliently rocks the link 853 in a direction to urge the detent 854 toward the ratchet wheel 850 and into engagement with the ratchet teeth.

A hand-operated spacing lever 868 is pivotally mounted intermediate its length on the stud 864 and has a forwardly directed arm 869 extending past the rearward portion of the lever 855 and provided at its forward end with a laterally offset tongue formation 870 which engages the upper edge of the lever 855 near the foot 858 on the rear end of this lever. The lever 868 has a rearwardly directed arm 871 the rearward end of which is provided with a formation of increased width in which spaced-apart notches 872 and 873 are provided and open to the rear end of the arm. The lever 868 i also provided with a third arm 874 upstanding from the portion of the lever mounted on the stud 863 and constituting a handle for rocking the lever 868 to manually control the single and double spacing operation of the tape feed.

A detent arm 875 is pivotally mounted at its lower end on a shaft 876 disposed above rearwardly of, and substantially parallel to the actuator bail shaft 185. This detent arm 875 is upwardly directed from the shaft 876 and carries near its upper end a laterally projecting stud 878 which is selectively receivable in the notches 872 and 873 in the rearward end of the arm 871 of the lever 868. The detent arm 875 is resiliently urged in a forward direction by a spring 880 connected between the distal end of a rearwardly projecting extension 881 of the detent lever 875 and the tie rod 831 which is disposed forwardly of the lever 875 intermediate the length of this lever.

With the above-described arrangement, when the upper end of the handle 874 is manually moved forwardly, the forward end of the arm 869 is moved downwardly depressing the rearward end of the lever 855 and setting the foot 858 for double spacing of the platen feed, the lever 868 being releasably retained in this position by engagement of the latch stud 878 in the notch 873, and when the upper end of the handle 874 is manually moved rearwardly, the front end of the lever arm 869 is raised thereby permitting the foot 858 on the rear end of the lever 855 to be raised by the spring and thereby set .the feed for single spacing operation, the detent stud 878 being at this time received in the notch 872 in the rear end of the arm 871, as is shown in Fig. 7. The projection 882 between thenotches 872 and 873 has divergently inclined edges and a rounded outer end so that the pin 878 will cam from one of the notches 872 or 873 to the other against the force of latching spring During the keyboard clearing cycle of the machine the v printing mechanism is restrained from printing and the chine and having a forwardlyidirected arm: 887, the distal-- 20 end of which is engaged by the keyboard clearing key in a manner to rock the lever 885 in a clockwise direc tion, as viewed in Fig. 8, when the keyboard clearing key is depressed. The lever 885 also has a rearwardly extending arm 889 provided at its rearward end with a transverse end edge or shoulder 890-which, when the keyboard clearing key is depressed, is moved under the cam follower 273 on the rocker arm 270 so that this cam follower cannot drop into the dwell 274 of the printing cam 172 to lower the print control bail rod 265 for printing movement of the unlatched print wheel carriers 221. An extension 891 of the arm 889 extends rearwardly from the terminal shoulder 890 and carrie at its rearward end a laterally projecting stud 892.

A shaft 894 is disposed transversely of the machine rearwardly of and above the shaft 807 and is journalled in the frame plates 186 and 187. An arm 895, secured at one end to the left-hand end of shaft 894 extends downwardly and forwardly from this shaft and has at its forward end a bifurcated formation providing a notch 896 receiving the stud 892 whereby the shaft 894 is rocked in a counter-clockwise direction, as viewed in Fig. 8, when the keyboard clearing key 586 is depressed.

A lever 897 (Fig. 7) is mounted intermediate its length on the right-hand end of shaft 894 and includes an upwardly and forwardly directed arm 898 having the upper portion of its rearward edge formed as a concave cam surface 899 disposed forwardly of and opposed to the stud 866. Since the counter-clockwise movement of shaft 894, as viewed in Fig. 8, becomes clockwise when viewed in Fig. 7, it is seen that depression of the key board clearing key will rock the shaft 894 in a direction to bring the cam surface 899 of lever 897 against stud 866 and hold the upper end of pawl link 853 away from ratchet wheel 850 thereby disabling the tape feeding mechanism.

As shown in Fig. 7, a guide roller 902 for the paper tape is disposed below the lower forward portion of the platen 242 and rotatably mounted at its end in bellcrank arms, as indicated at 903, pivotally mounted at their bends or angles on a shaft 904 extending transversely of the printing mechanism below the platen 242. The bellcrank levers have downwardly directed arms, as indicated at 905 and springs, as indicated at 906, connected between the lower ends of the arms 905 and the machine frame forwardly of these arms resiliently urge the guide roller 902 upwardly toward the lower portion of the platen surface.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

What is claimed is: p

1. In a calculating machine having an actuator mechanism including actuator sectors ordinally arranged and individually rockable to differentially set positions, printing mechanism comprising a platen, ordinally arranged print wheel carriers rockably mounted for movement about a common axis, print wheelsrotatably mounted one on each of said print wheel carriers and movable by the corresponding carriers toward and away from said platen, means drivingly connecting said actuator sectors to, said print wheels in corresponding orders for rotating said print wheels to angular positions at which they present to said platen print characters corresponding to the differential setting of the coordinate actuator sectors, means resiliently urging said print wheel carriers to move said print wheels toward said platen, blocking means restraining said print wheel carriers from moving said print wheels toward said platen, meansacting in timed reaware? lationship to the movement of "-said aotuator sectors moving said blocking means out of carrier =blocking position at a predetermined time in the movement of said actuator sectors, -said ,print wheels having a tull 'cycle rotational position from whichithey are moved by the corresponding actuator sectors in accordance with the differentialsetting of the latter,-and means operating intimed relationship to the movement of said actuator sectors latching those print wheel carriers to the' left of the print Wheels rotated from their full-cycle position againstmovemerit toward said platen when said blocking means is moved out -of blocking position relative to "said print wheel carriers,

2. In a calculating machine having an actuator mechanism including actuator sectors ordinally arranged and individually rockable to differentially set positions, printing mechanism comprising a platen, ordinally arranged print wheel carriers rockably mounted for movement about a common axis, print wheels rotatably mounted one on each of said print wheel carriers and movable by the corresponding carriers toward and away from said platen, means drivingly connecting said actuator sectors to said print wheels in corresponding orders for rotating said print Wheels to angular positions at which they present to said platen print characters corresponding to the differential setting of the coordinate actuator sectors, means resiliently urging said print wheel carriers to move said print wheels toward said platen, blocking means restraining said print wheel carriers from moving said print wheels toward said platen, means acting in timed relationship to the movement of said actuator sectors mov ing said blocking means out of carrier blocking position at a predetermined time in the movement of said actuator sectors, said print wheels having a full-cycle angular position from which they are moved by said actuator sectors when the latter move to their dilferentially set positions, and locking means operating in timed relationship to the movement of said actuator sectors looking said print wheels against rotational movement while the print wheels are being moved toward and away from said platen by said print wheel carriers.

3. In a calculating machine having selection mechanism, actuation mechanism including a plurality of ordinally arranged actuator racks differentially movable to positions determined by the setting of said selection mechanism, and gear transmission mechanism efiYective to drivingly connect the actuator racks of said actuating mechanism to said selection mechanism, printing mechanism including a platen, a plurality of ordinally arranged print wheel carriers pivotally mounted adjacent to and resiliently urged toward said platen, print wheels carried one by each of said carriers in opposition to said platen, intermediate gears carried one by each of said carriers and drivingly connected to the corresponding print wheels, print wheel drive gears rotatably mounted adjacent to and driven by said actuator racks and ordinally related to said actuator racks and said print wheels, said drive gears meshing with the corresponding intermediate gears to turn said print wheels to angular positions corresponding to the ditferentially set positions of said actuator racks and each having a full-cycle position corresponding to the position of the corresponding print wheel, means collectively restraining said carriers against movement toward said platen and movable in timed relationship to the movement of said actuator racks to free said print wheel carriers for movement toward said platen, latch means resiliently urged to position to engage said carriers and restrain said carriers against movement toward said platen, blocking means normally holding said latch means against movement to carrier engaging position and movable in timed relation ship to the movement of said actuatorracks to free said latch means to move to carrier engaging position, and

means conditioned by movement of said drive gears away;

from their full-cycle position to individually restrain said axis, and coordinally engaging said actuator sectors for rotation thereby, :print wheeldrive gearswrotatable about a common axis and coordinally engaging said transmission gears for rotation thereby, a cylindrical formation projecting coaxially from one side of each print wheel drive gear and having therein a notch which occupies a predetermined rotational position when the corresponding drive gear is in full-cycle position, a platen, ordinally arranged print wheel carriers rockably mounted for movement toward and away from said platen, a print wheel rotatably mounted on each print wheel carrier and provided with a gear formation, an intermediate gear,

rotatably mounted on each carrier and constantly in mesh with the corresponding print wheel gear formation and meshing with the coordinal print wheel drive gear when the corresponding carrier is in its full-cycle position away from said platen, means resiliently urging said print wheel carriers toward said platen, blocking means normally retaining said carriers in full-cycle position, cam operated means moving said blocking means to release said carriers for printing movement when said actuator sectors have been moved to their ditferentially set positions, and restore said carriers to their full-cycle position after printing, detents pivotally mounted on said print wheel carriers and resiliently urged to position to latch said print wheels against rotation, cam operated means effective to move said detents to print wheel latching position as said carriers are released for movement toward said platen and to restore said detents to their full-cycle, print wheel releasing position, when said carriers are returned to full-cycle position, zero foil latches mounted for rocking movement about a fixed axis and resiliently urged to a position in which they coordinally engage said print wheel carriers to retain said carriers in full-cycle position, each zero foil latch having an arm riding on the cylindrical formation of the coordinal print wheel drive gear and holding the latch in carrier releasing position except when-the notch in said formation is in angular position corresponding to the zero position movement to printing position, and a tongue formation on each zero foil latch, except the latch of lowest order, overlapping the tongue formation on the latch of next higher order to restrain zero foil latches of orders below the highest order print wheel which has been displaced from its 0 position from engaging the coordinal'print wheel carriers even though some or all of the print wheels of orders below said highest order displaced print wheel have not been displaced from their 0 positions.

5. In an adding machine, a platen, denominational printing wheels, a separate rockable arm rotatably supporting each said printing wheel, a yieldable biasing means urging each said wheel toward said platen, a printing bail normally holding said wheels away from said platen, power means for cyclically operating said bail from its normal holding position to a position in 

